CRYOGENIC FREEZING OF FOODS.

Abstract

Cryogenic freezing as applied to food, can be defined as very rapid freezing achieved by exposing food to a very cold refrigerant that usually undergoes a change of state while the food is being frozen. Cryogenic refrigerants of the greatest commercial importance are liquid nitrogen, liquid carbon dioxide and dichlorodifluoromethane. Equipment for cryogenic freezing usually takes the form of an insulated open-ended tunnel through which passes a variable-speed conveyor belt. In most instances, the quality of cryogenically frozen foods equals or exceeds that of conventionally frozen foods, provided that the period of frozen storage is limited to a few weeks or less and the temperature of frozen storage is minus 18 degree C or lower.